从有效氧胺A衍生的环己酮5制备了潜在的α-和β-葡萄糖苷酶抑制剂spirodiaziridines 6和9。5的三甲基甲硅烷基保护基对于以高收率形成6至关重要。氧化6得到7。所述diaziridine 6(对ķ HA = 2.6)和二吖丙因7不抑制β从杏仁葡糖苷酶,所述β从葡萄糖苷酶Caldocellum糖热厌氧杆菌,和α-酵母中的葡萄糖苷酶。N-苄基二氮丙啶9是α-葡萄糖苷酶的非常弱的抑制剂,但不抑制β-葡萄糖苷酶。为了观察弱抑制是由于二氮丙啶的碱度低还是由于几何因素所致,我们制备了螺氮丙啶21和25以及1-epivalidamine(32)。将已知的环己酮10甲基化并环氧化为16和17。16和17的叠氮基打开,甲磺酰化,LiAlH 4还原和脱保护得到氮丙啶21和25。1-Epivalidamine(32)由已知的氨基葡萄糖29制备。氮丙啶25(p K HA = 6.8)是来自糖化卡尔德
从有效氧胺A衍生的环己酮5制备了潜在的α-和β-葡萄糖苷酶抑制剂spirodiaziridines 6和9。5的三甲基甲硅烷基保护基对于以高收率形成6至关重要。氧化6得到7。所述diaziridine 6(对ķ HA = 2.6)和二吖丙因7不抑制β从杏仁葡糖苷酶,所述β从葡萄糖苷酶Caldocellum糖热厌氧杆菌,和α-酵母中的葡萄糖苷酶。N-苄基二氮丙啶9是α-葡萄糖苷酶的非常弱的抑制剂,但不抑制β-葡萄糖苷酶。为了观察弱抑制是由于二氮丙啶的碱度低还是由于几何因素所致,我们制备了螺氮丙啶21和25以及1-epivalidamine(32)。将已知的环己酮10甲基化并环氧化为16和17。16和17的叠氮基打开,甲磺酰化,LiAlH 4还原和脱保护得到氮丙啶21和25。1-Epivalidamine(32)由已知的氨基葡萄糖29制备。氮丙啶25(p K HA = 6.8)是来自糖化卡尔德
On the Origin of Regioselectivity in Palladium‐Catalyzed Oxidation of Glucosides
作者:Ieng Chim (Steven) Wan、Trevor A. Hamlin、Niek N. H. M. Eisink、Nittert Marinus、Casper Boer、Christopher A. Vis、Jeroen D. C. Codée、Martin D. Witte、Adriaan J. Minnaard、F. Matthias Bickelhaupt
DOI:10.1002/ejoc.202001453
日期:2021.1.26
The physical factors behind the remarkable site‐selectivity in palladium‐catalyzedoxidation of unprotected glucosides was uncovered. The regioselectivity is traced back to the presence of the ring oxygen which steers the reactivity in order to minimize inductive charge repulsion.
Biosynthesis of the Validamycins: Identification of Intermediates in the Biosynthesis of Validamycin A by <i>Streptomyces </i><i>h</i><i>ygroscopicus</i> var. <i>l</i><i>imoneus</i>
作者:Haijun Dong、Taifo Mahmud、Ingo Tornus、Sungsook Lee、Heinz G. Floss
DOI:10.1021/ja003643n
日期:2001.3.1
nitrogen atom linking the two pseudosaccharide moieties is not clear yet. 7-Tritiated valiolamine (8), valienamine (2), and validamine (3) were all not incorporated into 1, although each of these amines has been isolated from the fermentation, with 3 being most prevalent. Demonstration of in vivo formation of [7-(3)H]validamine ([7-(3)H]-3) from [7-(3)H]-12 suggests that 3 may be a pathway intermediate and
ValC, a New Type of C7-Cyclitol Kinase Involved in the Biosynthesis of the Antifungal Agent Validamycin A
作者:Kazuyuki Minagawa、Yirong Zhang、Takuya Ito、Linquan Bai、Zixin Deng、Taifo Mahmud
DOI:10.1002/cbic.200600528
日期:2007.4.16
thus suggesting a critical function of valC in validamycinbiosynthesis. In vitro characterization of ValC revealed a newtype of C7-cyclitolkinase, which phosphorylates valienone and validone--but not 2-epi-5-epi-valiolone, 5-epi-valiolone, or glucose--to afford their 7-phosphate derivatives. The results provide new insights into the activity of this enzyme and also confirm the existence of two
Synthesis of polyhydroxylated cyclohexenyl sulfides and sulfoxides. Evaluation of their inhibitory activity on α- and β-d-glucosidases
作者:André Lubineau、Isabelle Billault
DOI:10.1016/s0008-6215(99)00137-8
日期:1999.7
Racemic polyhydroxylated sulfides and sulfoxides have been prepared as potential transition-state analogs of the glucoside hydrolysis reaction, through a reaction sequence involving transformations of a ketone group into thioacetal, followed by partial oxidation to sulfoxide then regioselective thermal elimination of the sulfoxide to vinyl sulfide. These sulfides with two, three or four hydroxyl groups have been oxidized to the corresponding diastereoisomeric sulfoxides. All compounds, summarily tested as inhibitors of alpha- and beta-glucosidases, were found to be very weak inhibitors and thus their biological properties were not studied in depth. Curiously, however, their inhibitory properties, which are in the 10 mM range, do not really depend upon the number of hydroxyl groups or upon the presence of polar sulfoxide. In order to get more insights, 2-phenyl sulfoxide-3,4,5-trihydroxycyclohex-1-ene (9a) was studied in more detail using Brewers yeast alpha-glucosidase and was shown to give a mixed-type inhibition with a high K-i of 45 mM. (C) 1999 Elsevier Science Ltd. All rights reserved.